Present in every tissue of the body, ubiquitin appears to be involved in a dizzying array of functions, from cell cycle and division to organelle and ribosome biogenesis, as well as the response to viral infection. The protein plays at least two role

Despite its discovery as a protein that seems to show up everywhere, at least in eukaryotic cells, researchers are only beginning to scratch the surface of all of the cellular functions involving ubiquitin.